Ion-exchangeable glasses are used to produce chemically-strengthened glass articles, also known as ion-strengthened glass articles. Examples of ion-strengthened glass articles include the scratch-resistant faceplates used in portable electronic devices, e.g., the faceplates made from Corning Incorporated's Gorilla® brand glass sheets. In broad overview, such articles are made by forming an ion-exchangeable glass into a desired configuration, e.g., into a glass sheet in the case of faceplates, and then subjecting the formed glass to an ion-exchange treatment, e.g., a treatment in which the formed glass is submersed in a salt bath at an elevated temperature for a predetermined period of time.
The ion-exchange treatment causes ions from the salt bath, e.g., potassium ions, to diffuse into the glass while ions from the glass, e.g., sodium ions, diffuse out of the glass. Because of their different ionic radii, this exchange of ions between the glass and the salt bath results in the formation of a compressive layer at the surface of the glass which enhances the glass's mechanical properties, e.g., its surface hardness. The effects of the ion exchange process are typically characterized in terms of two parameters: (1) the chemical depth of layer (DOL) produced by the process and (2) the final maximum surface compressive stress (CS). Values for these parameters are most conveniently determined using optical measurements, and commercial equipment is available for this purpose, e.g., the stress meters sold by Orihara Industrial Company, Ltd. As used herein, DOL and CS values are values determined using such equipment.
As discussed in detail below, because of the number of variables that come into play, the selection of batch components for producing ion-exchangeable glasses has been a complicated, challenging, time-consuming, and expensive process. Consequently, the historical brute-force approach of producing numerous glass samples having different compositions, subjecting those samples to an ion-exchange process, and then testing the resulting ion-exchanged glasses for their DOL and CS values has been severely challenged by the ever-growing demand for improved ion-strengthened glass articles.
The present disclosure addresses this existing problem in the art and provides computer-implemented models that relate at least DOL and CS to batch composition. As shown by the working examples set forth below, through use of the computer-implemented models, glass compositions have been identified which achieve desirable, commercially-valuable balances between the competing requirements for an ion-exchangeable glass composition.